The present invention relates in general to devices which provide for the selective adjustment and positioning of movable structural components relative to one another. As will be seen, the device is ideally suited for use in furniture, particularly office furniture, where the current market emphasis on ergonomic design calls for adjustable furniture structures such as used with certain chairs that can be adjustably positioned to fit different individuals with various heights, weights and job tasks.
Primarily the device is intended for the positioning of components where frictional locking is sufficient and load forces moderate, such as with chair arms, but where it is desirable to avoid the use of friction inducing levers or other locking members. The adjustment device herein can be used to laterally position the arms of a chair to accommodate users of different body widths. In the prior art, chair arm lateral adjustment has been accomplished by means of structural members or "J- BARS" provided with elongated slots and bolted to the undercarriage or seat pan of the chair. One type of adjustment was accomplished by reaching under the chair with a specialized tool or wrench and loosening or tightening several bolts. Another type of adjustment, such as is the subject of my U.S. Pat. No. 5,338,133, for loosening or tightening by means of a lever which frictionally locks in one position or another. While the latter method was practical and effective it has the disadvantage of the presence of the actuating lever that tends to clutter the underside of the chair seat, where one already finds numerous levers pertaining to the adjustment of other adjustment devices on the chair. It has been found, that chair arms are normally subject to stress loads (such as by the occupant's arms), in any position of lateral adjustment, perpendicular to the chair seat. Little or no horizontal loads act on the chair arms. Therefore, it is felt that it would be possible and highly desirable to obtain positioning of the chair arms without the need for a "locking" function, and that all that is needed is the ability to laterally adjust the position of the arms and provide only a simple "detente" in any of several arbitrarily chosen positions, thus eliminating the need for a "locking lever". Alternately, where a "detente" is not required or may prove costly, the adjustment device may include only a frictional adjustment. The device and objective of the present invention provides for quick manual positioning of one structural member relative to another. In particular, where office chairs are concerned, the device may serve to laterally position chair arms relative to the chair seat at any of an arbitrarily chosen number of positions within a predetermined range (sometimes referred to as the "Stroke"), or, in the alternate method, at any of an infinite number of positions within the predetermined range (Stroke). It will appear clear from the subsequent specification that the device is not limited to use in chairs and articles of furniture but has many uses where reliable and economical structural adjustment is sought.